1885.] '"^ ' ^ [Genlh and Vom Rath. 



a2. 1.1043 grm of nearly pure brownish -red crj'stals gave 0.0135 grm 

 pyrolusite and quartz, giving 1.0682 grm pure vanadates, which gave 0.0017 

 grm Ag ;^ 0.0006 grm CI or 0.0226 gnu vanadinite, which amount being 

 deducted gave 1.0682 grm descloiziie, furnishing 0.8396 grm PbSO^. less 

 0239 grm for vanadinite or 0.8157 grm., 0.0098 grm CuO, 0.0043 grm 

 Mn;504, 0.0012 grm Fe^Oa, 0.2454 grm V A' less 0.0044 for vanadinite or 

 0.2410 grm, no P.fi.^ and 0.0036 grm MgjAs.^O^. The zinc was lost. 



a3. 0.9762 grm of the red crystals, which were freed with the greatest 

 care from all vanadinite, gave 0.0060 grm quartz or 0.9702 grm pure 

 material which gave : 0.0230 grm loss on ignition, 0.7426 grm PbSO^, 

 0.0121 grm CuO. 0.1727 grm ZnO, 0.0064 grm MnjO^, 0.0040 grm Fe.p,, 

 0.0022 grm Mg.^As.^^ and no P^O^. The VjO^ was determined by differ- 

 ence. 



In the average of the three analyses the percentage of MnO in al is 

 left out, because it is evidently too high. 



= 2.09 



1.98 



1. 

 = 1.13 



100.00 99.49 



c. Blackish-broicn crystals. 



cl. This analysis was made with the residue from which the best mate- 

 rial was selected for c2 and c3, especially with reference to the amount of 

 water present and the admixture of pyrolusite. 1.1004 grm gave on igni- 

 tion a loss of 0.0290 grm. The residue, containing 0.0288 grm quartz, 

 gave 0.0040 grm Fe203 and 0.0829 grm MnOj which were deducted as 

 impurities. In the analysis c2 the chlorine was determined which repre- 

 sents the vanadinite, and from this the corresponding quantities were cal. 

 culated for cl and c3. 0.9847 grm, free from SiO^, MnO^ and Fe.jOg would 

 contain 0.0402 grm vanadinite or 0.9445 grm descloizite which gave : 

 0.7579 grm PbSO^ less 0.0427 grm for vanadinite or 0.7152 grm, 0.0081 

 grm CuO, 0.1318 grm ZnO, 0.0326 grm MugO^, 0.0029 grm Fc.,©.,, 0.0068 

 grm MgjAs.p,, a trace of P.^ f^od 0.2052 grm, less 0.0079 grm for vana- 

 dinite or 0.1973 grm Y.Pj. 



c2. 1.1300 grm of the purest crystals gave: 0.0720 grm MnO.„ 0.0015 

 grm FcjOg and 0.0032 grm quartz, giving for the vanadates 1.0533 grm, 

 less 0.0442 grm vanadinite or 1.0091 grm descloizite, which gave: 0.8221 

 grmPbSO^, less 0.0470 grm for vanadinite, or 0.7751 grm, 0.0106 grm CuO, 



